Abstract This is a three year project designed to identify sources of reading and writing difficulty for students in adult basic education (ABE) programs. According to the 2013 OECD survey, a significant number of adults struggle to read at a level adequate to function effectively in our society. The problem of adult illiteracy has a significant negative impact on job acquisition, civic participation, and informed access to healthcare. Not surprisingly, the small but growing body of research on this population of readers suggests that their reading behavior differs in significant ways from that of children matched on reading achievement. Unfortunately, the basic research foundation upon which to build assessment and intervention tools targeted to the unique characteristics of adults learning to read is still greatly impoverished in relation to what is known about children learning to read (NICHD, 2001). Thus, much of the intervention and assessment material used in ABE programs is based upon what we know about children. This project will expand the basic research foundation necessary to build effective assessment and intervention programs targeted to the specific needs of this population. This project will compare the reading and writing behavior of two groups of participants (adults with less than a 7th grade reading level who are currently enrolled in ABE programs and children who are matched on reading ability). Both groups will be matched on socio-economic factors and ethnic and racial background. While phonological awareness is seen by many as the most important aspect of literacy acquisition, the English system of writing is not purely alphabetic, rather, it is morphophonemic; words are represented in writing according to their meanings as well as the way they sound. Thus, this project will focus on the contributions of morphological factors as they relate to reading and writing development. Furthermore, morphology has been identified as one component of vocabulary depth. Depth refers to how much we know about particular words compared to breadth which is how many words we know. The purpose of this study is to investigate the role of morphology in vocabulary depth. We will use a multi-skills approach to understand how morphological awareness and other aspects of vocabulary depth contribute to reading comprehension, visual word recognition in silent reading while eye movements are monitored, and writing in these two groups of learners. Performance across the two groups will be compared to gain a more detailed understanding of the unique characteristics of the adult learning to read.